The described invention relates in general to a system for detecting contaminants in biological samples. More specifically, the present invention relates to a system for detecting infectious agents or pathogens in food samples in real time using a reagent such as a biosensor.
Previously, testing of samples for infectious agents was a time consuming and expensive process that was largely divorced from the manufacturing process. In order to test for the presence of an infectious agent, a sample was typically enriched or cultured. This process requires the presence of a lab, and typically, the involvement of scientists with expertise in performing the required test. Due to the need for additional culturing or enriching time, and specialized tools and skills, the testing could not easily be performed on-site during the manufacturing process. As a consequence, the manufacturing process was typically divorced from the testing process, resulting in the need for costly recalls when the testing process later found the presence of infectious agents, and the like. In other settings, such as hospitals, delays in receiving test for infectious agents can allow for the spread of such infectious agents.
Several proposals have been made to improve the speed of testing for infectious agents by using biosensors for detection. For example, application of the aequorin-Ca2+ indicator to detect E. coli contamination in food products was reported by Todd H. Rider et al., A B Cell-Based Sensor for Rapid Identification of Pathogens, SCIENCE, 11 Jul. 2003, pp. 213-215, the entire disclosure of which is incorporated herein by reference. However, the Rider process suffered from several drawbacks, such as a low signal-to-noise ratio that resulted in the process being undependable for use in large scale testing.
In generic terms, a biosensor is a system or device for the detection of an analyte that combines a sensitive biological component with a physicochemical detector component. The components of a typical biosensor system include a biological element, a transducer or detector element, and associated electronics or signal processors that display test results in a meaningful and useful manner. The biological element includes biological material such as tissue, microorganisms, organelles, cell receptors, enzymes, antibodies, nucleic acids, and the like that may be created by known biological engineering processes. The transducer or detector element works in a physicochemical manner (e.g., optical, piezoelectric, and/or electrochemical) that transforms a signal resulting from the interaction of the analyte with the biological element into another signal that can be more easily measured and quantified. Biosensors originated from the integration of molecular biology and information technology (e.g., microcircuits, optical fibers, etc.) to qualify or quantify biomolecule-analyte interactions such as antibody-antigen interactions.
There is demand for rapid, sensitive, easy-to-handle, and cost-effective detection tools to detect infectious agents, pathogens or/and toxins in food (see, for example, Mead et al., Food Related Illness and Death in the United States, Emerging Infectious Diseases; Vol. 5, No. 5, September-October 1999 (607-625) which is incorporated by reference herein).
Accordingly, it is desirable to provide a portable, self-contained system capable of rapidly testing samples for infectious agents in real time or near real time. It is further desirable to improve the technique of using biosensors for testing samples for infectious agents by improving the signal-to-noise ratio. It is further desirable to provide a testing device capable of being used by general staff for testing foodstuffs while in the manufacturing process.